<PAGE>

                                                                   EXHIBIT 4(aa)

                                                                     TRANSLATION

This Credit Line Agreement No. 05CS24 is made and entered into by and among (i)
Ixe Banco, S.A., Institucion de Banca Multiple, Ixe Grupo Financiero, as lender
("Ixe Banco") and (ii) the person referred to in Exhibit 1 to this Agreement as
borrower (the "Borrower"); in accordance with the following representations and
clauses:

                                 REPRESENTATIONS

I. In order to obtain from Ixe Banco the credit subject matter of this
Agreement, Borrower represents under oath, and being aware of the content of
Article 112, paragraphs I and IV, of the Credit Institutions Act (Ley de
Instituciones de Credito) that:

(a) Borrower is a legal entity duly organized and validly existing under the
laws of its country of incorporation, duly capable to assume obligations under
this Agreement, and registered with the Federal Taxpayer Registry under the
registration number set forth in the Federal Taxpayer Number Section of Exhibit
1 to this Agreement.

(b) No legal action or proceeding has been brought before judicial or
administrative authorities against Borrower or its assets (having an adverse
effect thereon).

(c) Borrower has enough authority and capacity to enter into this Agreement, as
set forth in the Authority and Capacity Section of Exhibit 1 to this Agreement.

II. Ixe Banco represents to be a stock corporation (Sociedad anonima) duly
organized and authorized to act as commercial bank (Institucion de banca
MULTIPLE).

NOW, THEREFORE, the parties agree to grant the following:

                                     CLAUSES

1. DEFINITIONS.

Terms used in this Agreement shall have the following meanings ascribed to them,
whether in singular or plural form:

"Business Day" shall mean each and every day of the year in which banks are not
required to remain closed and suspend their activities, as provided for in
applicable regulations issued by the National Banking Commission and other
competent authorities.

"Checking Account" shall mean the checking account opened by Borrower at Ixe
Banco.

<PAGE>

"Checking Account Number" shall mean the number of the checking account opened
by Borrower at Ixe Banco set forth in the Checking Account Number Section of
Exhibit 1 hereto.

"Disbursement" shall mean any disbursement of the credit made under this
Agreement in accordance with Clause 4 below.

"Disbursement Deadline" shall mean the date set forth in the Disbursement
Deadline Section of Exhibit 1 hereto, or the date on which a suspension or
cancellation is notified to Borrower in accordance with Clause 5 below,
whichever occurs first.

"Disbursement Period" shall mean the period that will start on the execution
date of this Agreement and end on the date set forth in the Disbursement
Deadline Section of Exhibit 1 hereto.

"Interest Payment Date" shall mean the date on which interest accrued during the
calendar months of the Interest Period is to be paid; this is, the last day of
each month from the Disbursement of the credit.

"Interest Period" shall mean a one-calendar-month period, for calculating
interest accrued on the outstanding balance of principal of each Disbursement of
the credit, provided that the first period shall start on the date of the first
Disbursement and end on the closest Interest Payment Date (inclusive), and any
subsequent period shall start on the calendar day immediately succeeding the
immediate preceding Interest Payment Date and end on the next Interest Payment
Date (inclusive).

"Interest Rate" shall mean the sum of the Reference Rate and the Spread.

"Reference Rate" shall mean the inter-bank interest rate of equilibrium ("TIIE")
for 28-Day deposits published by the Central Bank of Mexico (Banco de Mexico) in
the Official Gazette of the Federation, taking as reference the rate effective
on the date on which each Interest Period starts, provided that if TIIE rate is
no longer published, any rate replacing the same shall apply, and in the absence
of the latter, the yield rate paid by 28-Day Treasury Certificates (CETES) for
primary placements shall apply, taking as a reference the rate effective on the
date on which each Interest Period starts. The annual rate shall be equal to the
gross yield or interest offered by this instrument.

"Spread" shall mean the basis points to be added to the Reference Rate.

2. CREDIT LINE.

Ixe Banco opens a credit line to Borrower up to the amount set forth in the
Credit Line Section of Exhibit 1 hereto (the "Credit Line"), which amount does
not include interest, fees and expenses, in accordance with Article 291 of the
Negotiable Instrument and Credit Transaction Act (Ley General de Titulos y
Operaciones de Credito), subject to the terms and conditions hereof; and
Borrower agrees to repay to

                                        2
<PAGE>

Ixe Banco any amounts disbursed by it in respect of the credit (the
"Disbursements") plus interest thereon, fees and other expenses, in accordance
with this Agreement.

3. CREDIT LINE'S PURPOSE.

The parties agree that the purpose of the credit line opened by Ixe Banco under
this Agreement in favor of Borrower is such purpose set forth in the Credit
Line's Purpose Section of Exhibit 1 hereto.

4. DISBURSEMENTS.

Borrower may disburse the credit, in whole or in part, in one or more
Disbursements by giving a written notice to Ixe Banco in the form of the
Disbursement Notice enclosed to this Agreement as Exhibit 2 and executing and
releasing promissory notes that shall meet the conditions referred to in Article
170 of the Negotiable Instrument and Credit Transaction Act, provided that any
Disbursement shall be made within the Disbursement Period.

5. SUSPENSION AND CANCELLATION OF THE CREDIT OR DISBURSEMENT PERIOD.

Ixe Banco shall be at all times entitled to suspend and cancel the Credit Line
or the Disbursement Period, or both at once, and terminate this Agreement. Upon
any suspension or cancellation of the Credit Line or the Disbursement Period, or
both of them at once, or any termination of the Agreement, any portion of the
credit not yet disbursed by the Borrower shall be cancelled.

Ixe Banco shall be entitled not to grant financing should its treasury be
prevented from granting credits in accordance with applicable regulations issued
by the Central Bank of Mexico or any other authority.

6. REPAYMENT.

Unless otherwise provided in this Agreement, Borrower shall repay the
Disbursements in such manner set forth in the Repayment Section of Exhibit 1 to
this Agreement, as well as in such manner established in any promissory notes
issued hereunder.

7. INTEREST.

Borrower agrees to pay to Ixe Banco:

(a) Interest.- Concerning the Disbursements made under the Credit Line, interest
on the outstanding daily balance thereof accrued during each Interest Period,
payable on the Interest Payment Date, which interest shall accrue at a rate
equal to the sum of the Reference Rate and the basis points set forth in the
Spread Section of Exhibit 1 hereto.

                                        3
<PAGE>

(b) Moratorium Interest.- Upon default in performance of any of the payment
obligations derived from this Agreement, moratorium interest on such outstanding
amount, at a rate equal to that resulting from multiplying the Interest Rate to
be applied under this Agreement effective during the time in which the default
continues without being cured by two (2).

Interest to be accrued under this Agreement shall be calculated on the basis of
a 360-calendar-day year and the actual number of days elapsed.

8. FEES AND EXPENSES.

Borrower hereby agrees to pay to Ixe Banco a front-end fee equal to the amount
resulting from multiplying the Credit Line by the percentage set forth in the
Front-End Fee Section of Exhibit 1 to this Agreement. This fee shall be paid at
the time in which the first Disbursement of the credit is made. Borrower further
agrees to bear each and every expense derived from, or related to, the
execution, performance and enforcement of this Agreement.

9. TERM.

This Agreement shall remain effective until the date set forth in the
Termination Date Section of Exhibit 1 to this Agreement (the "Termination
Date"). Borrower shall be obliged to pay any outstanding amount owed under this
Agreement, precisely on the Termination Date, regardless that the payment period
shall have not yet expired; provided, however, that the payment provisions set
forth in Clause 10 below and any other provisions relating to payment of
moratorium interest set forth in Clause 7, Paragraph (b), above shall remain
effective until the date on which all the amounts owed under this Agreement are
paid in full.

10. PAYMENTS.

Any payments to be made by Borrower under this Agreement (at maturity or upon
acceleration), which shall include but not be limited to the repayment of the
Disbursements, interest, fees and expenses shall be made as follows:

(a) Borrower shall make all the payments to Ixe Banco at the address of Ixe
Banco, in immediately available funds, by crediting the Checking Account of
Borrower. Thus, Borrower shall maintain enough funds to pay such amounts and, as
applicable, deposit (or credit in any other manner, additional Disbursement of
the credit excluded) the necessary funds as necessary to pay the owed amounts.
In order to perform the obligations derived from this Paragraph (a), Borrower
hereby expressly and irrevocably instructs and authorizes Ixe Banco to debit the
Checking Account for any amounts owed to Ixe Banco from time to time.
Notwithstanding the above, Ixe Banco may indicate any other place of payment by
giving a notice to Borrower, in which case Borrower shall make any payments
becoming due after the date of such notice in the place of payment indicated by
Ixe Banco.

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<PAGE>

(b) It is expressly understood that Borrower shall timely make the payments to
be made under this Agreement, subject to no payment request from Ixe Banco.

(c) Ixe Banco, at its exclusive discretion, shall allocate any amounts received
from Borrower in connection with the performance of its payment obligations
under this Agreement.

(d) The parties agree that the account statement prepared and certified by the
accountant of Ixe Banco entitled to do so in accordance with the Credit
Institutions Act, if any, shall suffice to determine: (i) the portion of the
Credit Line that Borrower may disburse, and (ii) the balance of the Credit Line
disbursed and to be repaid by Borrower, as well as interest, fees and expenses
to be paid by Borrower to Ixe Banco under this Agreement.

(e) Except for taxes to be paid by Ixe Banco in accordance with applicable laws,
if any, Borrower shall make all the payments to be made under this Agreement
free from any tax, withholding, contribution or duty (the "Taxes") levied or
imposed in any jurisdiction, whether federal, state or local. In the case such
Taxes are actually levied or imposed, Borrower shall pay an increased amount in
respect of any payment obligations to be performed under this Agreement such
that, after deduction of such Taxes, Ixe Banco receives the full amount it would
have received had the payment been made without deduction of such Taxes. In the
case that for any reason Ixe Banco pays any such Taxes, Borrower shall reimburse
to Ixe Banco the Taxes upon the agreed terms or demand payment thereof in any
other manner, as required by Ixe Banco. The obligations established in this
Paragraph (e) shall remain effective as long as the payment of such Taxes may be
enforced in accordance with applicable laws, regardless the termination of this
Agreement.

(f) Any payment to be made under this Agreement on a day that is not a Business
Day shall be made on the immediate succeeding Business Day.

(g) Reception by Ixe Banco of any amount on account of the Credit Line shall not
limit or terminate in any manner whatsoever the right of Ixe Banco to receive
interest or any other amount owed under this Agreement.

11. TRUST.

Simultaneously with the execution of this Agreement the Irrevocable Trust
created at BBVA Bancomer Servicios, S.A., Institucion de Banca Multiple, Grupo
Financiero BBVA Bancomer, Direccion Fiduciaria, as Trustee (the "Trust"), is
executed, so that such Trust may become an alternative source of payment and
guarantee for this credit, pursuant to which Ixe Banco will become a Trust
Beneficiary in the First Place, in respect of all the trust assets of the Trust.

Any cash flows forming part of the trust assets of the Trust shall be allocated
as an alternative source of payment for this credit, and therefore, any payment
made by the Trust to Ixe Banco, in its capacity as Trust Beneficiary in the
First Place, shall be

                                        5
<PAGE>

allocated by Ixe Banco to repay the credit up to the corresponding amount of
interest and principal thereof.

If Trustee fails to make any payment to Ixe Banco, in its capacity as Trust
Beneficiary in the First Place, or if the respective payments are not enough to
repay the outstanding balance of the credit, Borrower shall continue obliged to
repay the outstanding balance of the credit, plus any accrued interest, expenses
and court expenses and fees, if any.

If the payments made by Trustee to Ixe Banco, in its capacity as Trust
Beneficiary in the First Place, are not enough to repay the respective amount,
such payment shall be allocated in the following order of priority: moratorium
interest, if any, interest, and principal.

Consequently, Borrower may not transfer, dispose, or assign in any manner
whatsoever the assets or rights that form part of the trust assets of the Trust,
without the prior written consent of Ixe Banco.

12. EVENTS OF DEFAULT.

Ixe Banco shall be entitled, but not obliged, to accelerate the outstanding
balance of principal owed under this Agreement, interest accrued thereon, and
any other amounts owed under this Agreement should any of the following events
occur, in which case the outstanding balance of principal, interest accrued
thereon and any other amount owed under this Agreement shall immediately become
due and payable by Borrower, without requiring any further request, notice or
communication:

(a) If Borrower fails to timely pay the Disbursements, interest, fees, expenses
or other amounts owed under this Agreement; or

(b) If any representation made by Borrower turns to be false or misleading, or
any certificate or document submitted to Ixe Banco by Borrower turns to be fake;
or

(c) If Borrower fails to perform any obligation, agreement or contract that
needs to be performed under this Agreement, which shall include but not be
limited to, the affirmative and negative covenants set forth in Exhibit 3 to
this Agreement; or

(d) If Borrower is adjudged insolvent or bankrupt; or if Borrower assigns a
material part of its assets in favor of its creditors; or if Borrower is
deprived of possession, custody or control of a material part of its assets or
business as a consequence of any expropriation, seizure or intervention by any
governmental authority; or

(e) If Borrower fails, or is about to fail, to perform its obligations and
duties derived from any other agreement or contract pursuant to which Borrower
receives loans or credits from Ixe Banco or other financial entities; or

                                        6
<PAGE>

(f) If Borrower makes any change of control during the term of this Agreement,
without the prior consent of Ixe Banco; or

(g) If Borrower carries out any act aimed at selling, or creating a lien on, its
assets other than in the ordinary course of business of Borrower, during the
term of this Agreement; or

(h) If Borrower pays any dividends during the term of this Agreement without the
prior written consent of Ixe Banco; or

(i) If the credit's proceeds are not utilized for the purposes set forth in the
Credit Line's Purpose Section of Exhibit 1 hereto; or

(j) If Borrower fails to perform any of its labor or tax payment obligations,
and such failure continues without being cured upon expiration of a
15-calendar-day period; or if any labor or tax problems arise, posing a risk
with respect to the continuation of the regular operation of the Borrower; or

(k) If Borrower grants any guarantee, bond or security other than in the
ordinary course of business of Borrower during the term of this Agreement,
without the prior written consent of Ixe Banco; or

(l) If Borrower assumes financial liabilities, without the prior written consent
of Ixe Banco.

Without prejudice to the above, if any of the aforementioned events attributable
to Borrower occurs, Borrower shall pay to Ixe Banco interest on the Credit Line
at a rate equal to such rate referred to in Clause 7, paragraph (b) above, which
interest shall accrue from the date on which the respective default occurs to
the date on which Borrower pays the corresponding amount to Ixe Banco in full,
regardless of the right of Ixe Banco to demand payment of the credit in full.

If at any time Ixe Banco judicially demands the performance of any of the
obligations of Borrower derived from this Agreement, Ixe Banco shall indicate,
at its sole discretion, the assets to be seized, without following the order
established in Articles 536 and 537, paragraph I, of the Code of Civil
Procedures for the Federal District (Codigo de Procedimientos Civiles para el
Distrito Federal), and 1395 of the Commercial Code (Codigo de Comercio).

13. OTHER COVENANTS OF BORROWER; AND OTHER RIGHTS OF IXE BANCO.

In addition to the obligations of Borrower derived from this Agreement, during
the term hereof, Borrower shall be subject to the covenants set forth in Exhibit
3 to this Agreement.

The parties further agree that Ixe Banco shall be entitled to terminate this
Agreement or proceed in accordance with Clause 5, without being subject to any
responsibility,

                                        7
<PAGE>

should any events occur affecting the financial system and preventing Ixe Banco
from funding the granting of the Credit Line subject matter of this Agreement,
as a result of any (i) action taken by competent governmental authorities; or
(ii) event of public notoriety beyond the control of Ixe Banco.

14. ASSIGNMENT; DISCOUNT.

Ixe Banco shall be at all times entitled to assign or discount its rights and
obligations derived from this Agreement, in whole or in part. In order to ease
the negotiation of any assignment or discount of the credit subject matter of
this Agreement, with the prior consent of Ixe Banco, Borrower shall execute one
or more promissory notes in favor of IXe Banco in the total amount of the Credit
Line, including, as applicable, interest and moratorium interest accrued under
this Agreement, until the time in which the respective assignment or discount
takes pace, as well as any other documents necessary to carry out such
assignment or discount.

Borrower may not sell, assign, encumber, or otherwise transfer or dispose of its
rights and obligations derived from this Agreement, without the prior written
consent of Ixe Banco.

Borrower hereby expressly authorizes Ixe Banco to assign, negotiate and discount
any executed promissory notes, event before the maturity date thereof, in which
case the granted guarantees and securities shall remain effective.

15. INCREASED COSTS.

If any law, regulation, ruling or otherwise provision (which shall include but
not be limited to any requirements governing reserves, deposits, taxes or other
conditions) that Ixe Banco or any of its offices in charge of funding or
managing the Disbursements must abide by is amended after the execution date of
this Agreement, or construed in any different way by any court of competent
jurisdiction, or any event (whether beyond the control of Borrower or not)
occurs, as a result of which the necessary costs of Ixe Banco to make or
maintain effective the Disbursements of the credit are increased, or the amounts
received or to be received by Ixe Banco are reduced, Borrower shall pay to Ixe
Banco, upon request of the latter, on the last day of the Interest Period
effective at that time, any additional, reasonable and duly evidenced amounts
required to compensate Ixe Banco for such increased costs or reduced income. In
the aforementioned request, Ixe Banco shall mention the events that caused such
increased costs or reduced income and the respective calculation, which shall
become final and binding upon Borrower, unless such calculation involves
manifest error. If Ixe Banco requests payment of any additional amounts in
accordance with the above, Borrower, at its discretion, may earlier pay within a
30-day period from the respective request, the Disbursements of the credit
subject to no penalty whatsoever, together with any interest accrued from the
latest Interest Payment Date to the corresponding early payment date.

                                        8
<PAGE>

16. NOTICES.

Any notices and communications to be given by the parties under this Agreement
shall be given at the addresses referred to in the signature page thereof, which
addresses shall remain effective as long as no other address is notified. Ixe
Banco may give any notices and communications to be given under this Agreement
to Borrower via fax at the telephone number of Borrower referred to in the
signature page hereof.

17. ENTIRE AGREEMENT; AMENDMENTS.

This Agreement and Exhibits 1, 2 and 3 hereto constitute one and the same
Agreement, and no amendment thereto shall become effective, unless if in writing
and signed by Ixe Banco and Borrower.

18. EXECUTIVE INSTRUMENT.

This Agreement and the account statement certified by the public accountant of
Ixe Banco authorized to do so shall constitute an executive instrument, without
requiring any acknowledgment of signature or other requirement.

19. ACTS OF GOD.

In accordance with Article 2111 of the Civil Code for the Federal District
(Codigo Civil para el Distrito Federal), Borrower shall be obliged to perform
each and every of its obligations derived from this Agreement, even upon
occurrence of an Act of God.

20. GOVERNING LAW AND JURISDICTION.

This Agreement shall be governed by, and construed in accordance with, the laws
of the Federal District, United Mexican States. The parties expressly submit to
the jurisdiction of the courts sitting in the Federal District, United Mexican
States, waiving any other jurisdiction they may be entitled to by reason of
their domiciles or the location of their assets.

21. HEADINGS.

Headings of the clauses of this Agreement are only for reference purposes, and
therefore, not necessarily define, limit or describe the content thereof.

IN WITNESS WHEREOF, this Agreement and the Exhibits hereto are signed in 4
originals this 13th day of April, 2005, in Mexico City, Federal District, on the
date first written above, provided that Borrower keeps one original thereof, Ixe
Banco keeps two originals thereof, and the corresponding Notary Public keeps the
remaining original.

                                        9
<PAGE>

          BORROWER                                 IXE BANCO

MAXCOM TELECOMUNICACIONES,          IXE BANCO, S.A., INSTITUCION DE BANCA
       S.A. DE C.V.                 MULTIPLE, IXE GRUPO FINANCIERO

/s/ Gonzalo Alarcon Iturbide and             Patricia Ferro Bertolo and
Jorge Lopez Aguado Jimeno                    Armando Jorge Rivero Laing

________________________________    _______________________________________
Represented by Gonzalo Alarcon      Represented by Patricia Ferro Bertolo
Iturbide and Jorge Lopez Aguado     and Armando Jorge Rivero Laing
Jimeno
Address: Guillermo Gonzalez         Address: Av. Periferico Sur No. 314
Camarena No. 2000                   Col. San Angel Tlacopac
Col. Centro Ciudad Santa Fe         C.P. 01049, Mexico, D.F.
C.P. 01210 Mexico, D.F.             Telephone Number: 5174-2222
Telephone Number: 5147-1111

                                       10
<PAGE>

                                    EXHIBIT 1

Credit Line Agreement identified herein below (the "Agreement")

<TABLE>
<S>                                 <C>
Agreement No:                       05cs24

Checking Account Number:            1154961-0

Parties:                            1) Borrower: Maxcom Telecomunicaciones,
                                    S.A. de C.V., represented by
                                    Messrs. Gonzalo Alarcon Iturbide and
                                    Jorge Lopez Aguado Jimenez, as
                                    borrower (the "Borrower").

                                    2) Ixe Banco: Ixe Banco, S.A.,
                                    Institucion de Banca Multiple, Ixe
                                    Grupo Financiero, represented by
                                    Patricia Ferro Bertolo and Armando
                                    Jorge Rivero Laing, as creditor
                                    ("Ixe Banco").

Date:                               April 13, 2005

Federal Taxpayer Number:            MTE-960228-KL0

Credit Line:                        One hundred Million 00/100 Pesos
                                    ($100'000,000)

Credit Line's Purpose:              Coverage expansion.

Disbursement Deadline:              October 13, 2005

Repayment:                          By means of 24 monthly and consecutive
                                    installments of principal, on the payment
                                    dates and in the due amounts set forth in
                                    the Disbursement Notices and Promissory
                                    Notes derived from this Agreement.

Spread:                             Three (3) basis points.

Front-End                           Fee: One percent (1%) over the
                                    Amount of the Credit Line, payable
                                    on the date of the first
                                    Disbursement of the credit.

Termination Date:                   April 30, 2007
</TABLE>

                                       11
<PAGE>

Authority and Capacity:

PATRICIA FERRO BERTOLO AND ARMANDO JORGE RIVERO LAING evidence their authority
and capacity as representatives of Ixe Banco by means of the following public
instruments:

1. Public Instrument No. 32,541 dated August 1, 1994, which was granted before
Roberto Courtade Bevilacqua, Esq., Notary Public No. 132 in and for the Federal
District, and registered on November 22, 1994 with the Public Registry of
Commerce of the Federal District under Commercial Folio No. 193,508, evidencing
the incorporation of Banco Fimsa, S.A.

2. Public Instrument No. 33,450 dated May 3, 1995, which was granted before
Roberto Courtade Bevilacqua, Esq., Notary Public No. 132 in and for the Federal
District, and registered on January 4, 1996 with the Public Registry of Commerce
of the Federal District under Commercial Folio No. 193,508, evidencing a change
of the corporate name of Banco Fimsa, S.A., Institucion de Banca Multiple, Fimsa
Grupo Financiero to Ixe Banco, S.A., Institucion de Banca Multiple, Ixe Grupo
Financiero.

3. Public Instrument No. 7,320 dated October 31, 2000, which was granted before
Mario Evaristo Vivanco Paredes, Esq., Notary Public No. 67 in and for the
Federal District, and registered on March 16, 2001 with the Public Registry of
Commerce of the Federal District under Commercial Folio No. 193,508, evidencing,
among other things, the granting of a power of attorney to administer property
in favor of Mr. Armando Jorge Rivero Laing to be exercised jointly with another
attorney-in-fact vested with the same powers.

4. Public Instrument No. 107,346 dated March 4, 2005, which was granted before
Cecilio Gonzalez Marquez, Esq., Notary Public No. 151 in and for the Federal
District, and not yet registered with the Public Registry of Commerce of the
Federal District, evidencing, among other things, the granting of a power of
attorney to administer property in favor of Patricia Ferro Bertolo to be
exercised jointly with another attorney-in-fact vested with the same powers.

GONZALO ALARCON ITURBIDE AND JORGE LOPEZ AGUADO JIMENO evidence their authority
and capacity as representatives of Maxcom Telecomunicaciones, S.A. de C.V. by
means of the following public instruments:

1. Public Instrument No. 86,115 dated February 28, 1996, which was granted
before Ignacio Soto Borja, Esq., Notary Public No. 129 in and for the Federal
District, and registered on June 11, 1996 with the Public Registry of Commerce
of the Federal District, evidencing the incorporation of Amaritel, S.A. de C.V.

2. Public Instrument No. 2,967 dated May 21, 1998, which was granted before
Alberto T. Sanchez, Esq., Notary Public No. 83 in and for the Federal District,
and registered with the Public Registry of Commerce of the Federal District
under

                                       12
<PAGE>

Commercial Folio No. 210,585, evidencing an amendment to the by-laws of the
corporation in their entirety.

3. Public Instrument No. 55,145 dated February 9, 1999, which was granted before
Miguel Alessio Robles, Esq., Notary Public No. 19 in and for the Federal
District, and registered on March 16, 1999 with the Public Registry of Commerce
of the Federal District under Commercial Folio No. 210,585, evidencing a change
of the corporate name of the Corporation to Maxcom Telecomunicaciones, S.A. de
C.V.

4. Public Instrument No. 56,631 dated October 11, 2002, which was granted before
Carlos Catano Muro Sandoval, Esq., Notary Public No. 51 in and for the Federal
District, and registered on December 2, 2002 with the Public Registry of
Commerce of the Federal District under Commercial Folio No. 210,585, evidencing
the granting of a power of attorney to administer property and for lawsuits and
collections in favor of Messrs. Gonzalo Alarcon Iturbide and Jorge Lopez Aguado
Jimenez, to be exercised individually.

General Data:

PATRICIA FERRO BERTOLO, a Mexican citizen born in Mexico City, Federal District
on the 11th day of February, 1967, married, banking officer, addressed at
Periferico Sur No. 314, Colonia San Angel Tlacopac, C.P. 01049, Mexico, D.F.

ARMANDO JORGE RIVERO LAING, a Mexican citizen born in Mexico City, Federal
District on the 3rd day of September, 1963, married, attorney, addressed at
PEriferico Sur No. 314, Colonia San Angel Tlacopac, C.P. 01049, Mexico, D.F.

GONZALO ALARCON ITURBIDE, a Mexican citizen born in Mexico City, Federal
District, on the 20th day of June, 1969, married, attorney, addressed at
Guillermo Gonzalez Camarena No. 2000, Col. Centro Ciudad, Santa Fe, C.P. 01210,
Mexico, D.F., Federal Taxpayer Number AAIG-690620-AK8.

JORGE LOPEZ AGUADO JIMENO, a Mexican citizen born in Mexico City, Federal
District, on the 21st day of March, 1959, married, public accountant, addressed
at Guillermo Gonzalez Camarena No. 2000, Col. Centro Ciudad, Santa Fe, C.P.
01210, Mexico, D.F., Federal Taxpayer Number LOJJ-590321-IU6.

IN WITNESS WHEREOF, the parties execute this Exhibit 1 to the Agreement on the
13th day of April, 2005.

                                       13
<PAGE>

            BORROWER                             IXE BANCO

MAXCOM TELECOMUNICACIONES,          IXE BANCO, S.A., INSTITUCION DE BANCA
       S.A. DE C.V.                 MULTIPLE, IXE GRUPO FINANCIERO

/s/ Gonzalo Alarcon Iturbide and             Patricia Ferro Bertolo and
Jorge Lopez Aguado Jimeno                    Armando Jorge Rivero Laing

Represented by Gonzalo Alarcon      Represented by Patricia Ferro Bertolo
Iturbide and Jorge Lopez Aguado     and Armando Jorge Rivero Laing
Jimeno

                                       14
<PAGE>

                                    EXHIBIT 2

Disbursement Notice under the Credit Line Agreement No. 05CS24 identified herein
below.

                               DISBURSEMENT NOTICE

                                                          _______________, 20___

IXE BANCO, S.A., INSTITUCION DE BANCA MULTIPLE
IXE GRUPO FINANCIERO

Dear Sirs:

In accordance with Clause 4 of the Credit Line Agreement No. 05cs24 dated April
13, 2005 by and between the undersigned, Maxcom Telecomunicaciones, S.A. de
C.V., and Ixe Banco, S.A., Institucion de Banca Multiple, Ixe Grupo Financiero
(the "Agreement"), I hereby inform you our intention to disburse the amount of
_______________ from the Credit Line. Consequently, I hereby instruct Ixe Banco
to deposit such amount to the Checking Account Number [1154961-0] opened with
such institution, in accordance with the Agreement.

The amount to be deposited to the aforementioned checking account out of the
Credit Line pursuant to these instructions shall be utilized for ___________.

Following are the Spread and Repayment applicable to this disbursement:

Spread: [__________] Repayment: [_____________]

Reception of this notice and the deposit by Ixe Banco of the disbursed amount to
the aforementioned checking account shall constitute undisputed evidence of the
disbursement of the funds under the Agreement, provided that the disbursement
requested hereby shall be subject to the applicable terms and conditions set
forth in the Agreement.

                                  Truly yours,

BORROWER
Maxcom Telecomunicaciones, S.A. de C.V.

________________________________
By: Gonzalo Alarcon Iturbide and Jorge Lopez Aguado Jimeno

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<PAGE>

IN WITNESS WHEREOF, the parties execute this Exhibit 2 to the Agreement on the
13th day of April, 2005.

          BORROWER                                IXE BANCO

MAXCOM TELECOMUNICACIONES,         IXE BANCO, S.A., INSTITUCION DE BANCA
        S.A. DE C.V.               MULTIPLE, IXE GRUPO FINANCIERO

/s/ Gonzalo Alarcon Iturbide and            Patricia Ferro Bertolo and
Jorge Lopez Aguado Jimeno                   Armando Jorge Rivero Laing

Represented by Gonzalo Alarcon     Represented by Patricia Ferro Bertolo
Iturbide and Jorge Lopez Aguado    and Armando Jorge Rivero Laing
Jimeno

                                       16
<PAGE>

                                    EXHIBIT 3

Affirmative and Negative Covenants of Borrower under the Credit Line Agreement
identified herein below (the "Agreement")

<TABLE>
<S>                        <C>
Agreement No:              05cs24

Checking Account Number:   1154961-0

Parties:                   1) Borrower: Maxcom Telecomunicaciones,
                           S.A. de C.V., represented by Messrs.
                           Gonzalo Alarcon Iturbide and Jorge Lopez Aguado
                           Jimenez, as borrower (the "Borrower").

                           2) Ixe Banco: Ixe Banco, S.A.,
                           Institucion de Banca Multiple, Ixe
                           Grupo Financiero, represented by
                           Patricia Ferro Bertolo and Armando
                           Jorge Rivero Laing, as creditor
                           ("Ixe Banco").

Date:                      April 13, 2005
</TABLE>

1. AFFIRMATIVE COVENANTS OF BORROWER.

During the term of the Agreement and until the Disbursements, interest, fees,
expenses and any other amount owed to Borrower under the Agreement are paid in
full, Borrower shall:

a) Provide Ixe Banco, within a 30-calendar-day period from the closing of each
quarter, with non-audited financial statements for the immediately preceding
quarter, duly signed by the Chief Executive Officer or the Chief Financial
Officer or equivalent officer, together with a report confirming whether an
event of default has occurred under the Agreement or not, as of the date of such
financial statements, provided that if an event of default has occurred, the
nature thereof and any actions already taken, or to be taken, to cure the same
shall be further mentioned.

b) Provide Ixe Banco, within a 120-calendar-day period from the closing of the
fiscal year, with annual financial statements (balance sheet, income statements,
cash flow), audited and certified by a public accountant firm satisfactory to
Ixe Banco, together with a letter signed by the Chief Executive Officer or the
Chief Financial Officer or equivalent officer, confirming whether an event of
default has occurred under the Agreement or not, as of the date of such
financial statements, provided that if an event of default has occurred, the
nature thereof and any actions already taken, or to be taken, to cure the same
shall be further mentioned.

                                       17
<PAGE>

c) Notify to Ixe Banco, within a 15-calendar-day period from the date on which
Borrower learns the same, any event that constitutes, or may constitute with
lapse of time, an event of default, together with a statement detailing such
event and the actions already taken, and to be taken to cure the same.

d) Notify to Ixe Banco, within a 15-calendar-day period from the date on which
Borrower learns the same, any (i) claim, complaint, lawsuit, proceeding, action
or arbitration before any administrative or judicial authority or arbitral
panel, whether domestic or international, that has or may have a material
adverse effect on the business, operation or assets of Borrower, (ii) labor
conflict that has or may have a material adverse effect on the business,
operation or assets of Borrower, and (iii) other contingent liability or
responsibility of Borrower that has or may have a material adverse effect on the
business, operation or assets of Borrower.

e) Comply with any applicable laws, regulations, decrees, rules and orders of
any nature that Borrowers must abide by, which shall include but not be limited
to, the punctual payment of any taxes, contributions and charges imposed on
Borrower and its assets.

f) Maintain valid and effective any licenses, authorizations, concessions,
permits, or registrations held by Borrower on the execution date of the
Agreement, and obtain any licenses, authorizations, concessions, permits or
registrations required in the future in the ordinary course of business of
Borrower in order to perform its obligations derived from the Agreement.

g) Keep its accounting records in accordance with Mexican generally accepted
accounting principles, properly reflecting its operations, assets and financial
condition.

h) Maintain all the assets necessary for its operation in sound condition and
make any necessary repairs, replacements, additions and improvements.

i) Permit Ixe Banco to visit its offices and premises and review its accounting
records, providing Ixe Banco with any clarifications reasonably requested in
respect of such records, provided that the same is requested no less than 15
calendar days before the intended date.

j) Maintain the same shareholding structure during the term of this Agreement,
unless otherwise authorized in writing by Ixe Banco.

k) Perform its payment obligations derived from any credit or loan granted to it
by Ixe Banco or any other financial entity.

l) Maintain its business in operation, without changing its corporate purpose
and legal nature.

                                       18
<PAGE>

2. NEGATIVE COVENANTS OF BORROWER.

During the term of the Agreement and until the Disbursements, interest, fees,
expenses and any other amount owed to Borrower under the Agreement are paid in
full, Borrower shall not:

a) Carry out any action aimed at dissolving, liquidating, transforming, merging
or spinning-off Borrower, or reducing its minimum capital stock, without the
prior written consent of Ixe Banco.

b) Sell, or create any lien or encumbrance on, the assets of Borrower, other
than in the ordinary course of business, without the prior written consent of
Ixe Banco.

c) Pay dividends, without the prior written consent of Ixe Banco.

d) Assume financial liabilities, without the prior written consent of Ixe Banco.

IN WITNESS WHEREOF, the parties execute this Exhibit 3 to the Agreement on the
13th day of April, 2005.

          BORROWER                                IXE BANCO

MAXCOM TELECOMUNICACIONES,         IXE BANCO, S.A., INSTITUCION DE BANCA
        S.A. DE C.V.               MULTIPLE, IXE GRUPO FINANCIERO

/s/ Gonzalo Alarcon Iturbide and         Patricia Ferro Bertolo and
Jorge Lopez Aguado Jimeno                Armando Jorge Rivero Laing

Represented by Gonzalo Alarcon     Represented by Patricia Ferro Bertolo
Iturbide and Jorge Lopez Aguado    and Armando Jorge Rivero Laing
Jimeno

                                       19
<PAGE>

Instrument No.: ________________

In Mexico City, Federal District, on this 13th day of April, 2005, I, Maria
Esther Garcia Alvarez, Public Broker No. 4 in and for the Federal District,
hereby attest that:

On this date, Patricia Ferro Bertolo and Armando Jorge Rivero Laing (acting in
their capacity as legal representatives of Ixe Banco, S.A., Institucion de Banca
Multiple, Ixe Grupo Financiero), Gonzalo Alarcon Iturbide and Jorge Lopez Aguado
Jimeno (acting in their capacity as legal representatives of Maxcom
Telecomunicaciones, S.A. de C.V.), and Jose Antonio Solbes Alvarez and Adrian
Aguirre Gomez (acting in their capacity as legal representatives of Maxcom SF,
S.A. de C.V.), which in the preceding Credit Line Agreement No. 05sc36 were
identified as Ixe Banco, Borrower and Joint and Several Obligor, respectively,
appeared before me in order to ratify such agreement in its entirety, stating
that the content thereof truly reflects their will and that the signatures
affixed therein are authentic and were affixed by them, all of which is stated
under oath and confirmed by signing this instrument before me.

           BORROWER                                IXE BANCO

MAXCOM TELECOMUNICACIONES,         IXE BANCO, S.A., INSTITUCION DE BANCA
       S.A. DE C.V.                MULTIPLE, IXE GRUPO FINANCIERO

     [Signed]      [Signed]
--------------------------------   _____________________________________________
Represented by Gonzalo Alarcon     Represented by Patricia Ferro Bertolo
Iturbide and Jorge Lopez Aguado    and Armando Jorge Rivero Laing
Jimeno

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